1. Field of the Invention
The present invention relates generally to providing cool dry air and more particularly to a method and apparatus for removing moisture from a liquid desiccant using distillation.
2. Description of the Prior Art
It is desirable in many industries such as breweries, meat and food packaging and processing and storage facilities to require cooled air that is also dry. When ambient air containing a particular amount of moisture is cooled, it is well known that the relative humidity increases. If the temperature is taken below the dew point, condensation takes place. Even at temperatures above the dew point, air with high relative humidity is undesirable. To achieve cool and also dry air, some form of dehumidification is necessary. The use of a solid or liquid desiccant are two methods for removing moisture. Liquid desiccants are easier to manipulate than solid desiccants and are hence preferred. A major problem is that the desiccant, if not continually exchanged, becomes saturated and hence useless. It is therefore desirable to have a continuous flow system where the absorbed moisture is continually removed from the desiccant and the desiccant is regenerated and re-used.
It is well known in the art to use liquid desiccants such as glycols, alcohols, ketones and other substances to remove moisture from gases. Landreau et al. in U.S. Pat. No. 6,004,380 and U.S. Pat. No. 6,461,413 teach drying natural gas using glycols and regenerating the desiccant. Parodowski in U.S. Pat. No. 5,670,027 teaches distillation of a liquid desiccant such as an alcohol or acetone. Lyon et al. in U.S. Pat. No. 4,009,083 teach regeneration of a an acid gas absorbing liquid using elevated pressure. Lermite et al. teach regeneration of a desiccant using a stripping agent.
It would be highly advantageous to have a system and method to dry cool air using a liquid desiccant that can be regenerated to an acceptable purity level up to 97% using inexpensive, readily available equipment such as a distillation column and condenser, and inexpensive available energy such as from steam or natural gas. Electricity could also be used.